Remove all instances of `AsRef<Path>` to reduce the amount of generated code

[oeb25]

This reduces LLVM lines from 1335068 to 1227782, which is a 8% decrease!

Unfortunetly it does not (yet) yield any compile-time benefits. These are the results of incremental cargo build:

Branch	Mean [s]	Min [s]	Max [s]	Relative
main	8.119 ± 0.066	8.012	8.264	1.00 ± 0.01
purge	8.084 ± 0.054	8.016	8.182	1.00

Benchmarks are run using the following command:

```bash hyperfine --show-output -w 2 --export-markdown bench-compile-main-vs-purge.md \ -p "git switch main && touch core/src/lib.rs && sleep 1" -n "main" "cargo build" \ -p "git switch purge-as-ref-path && touch core/src/lib.rs && sleep 1" -n "purge" "cargo build" ```

[oeb25]

I'll close this for now, since it does not provide much benefit.